25% of species at risk of extinction

About 25% of all species are officially threatened with extinction [1,2]. While it is natural that species go extinct [3], normally as many new species form as go extinct [4]. So most of the time the total number of species stays relatively constant [4].

BUT: Now humans are causing many more species to go extinct than would naturally [1,3]. For example, humans have increased the extinction rate for birds to 100x above the “natural” rate [1,3], and this may increase to 1000x over the next century [3]. Climate change plays a major and increasing role in driving decline of species populations, and extinction [2]. We will explore “how” over the next few posts.